2021

Permanent URI for this collectionhttps://hdl.handle.net/1807/104117

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A versatile protoplast system and its application in Cannabis sativa L.
(Canadian Science Publishing, 2021-12-04) Zhu, Panpan; Zhao, Yuqing; You, Xiner; Zhang, Yiping Jason; Vasseur, Liette; Haughn, George; Liu, Yuanyuan
Cannabis sativa L. (cannabis) is one of the earliest domesticated crops cultivated for medicinal, food, industrial, and recreational use throughout the world. A growing number of jurisdictions have lifted the prohibition on medical and recreational cannabis with legislation that allows researchers to conduct important and urgently needed research, such as understanding the molecular basis of agronomically important traits. However, a dearth of suitable molecular genetic techniques for the analysis of cannabis species has hampered the elucidation of gene function. Here, we developed a robust protoplast transient transformation system by optimizing conditions of protoplast isolation and PEG-mediated transformation using cannabis cotyledons. A protoplast isolation yield of up to 1.15× 107 cells per gram of fresh material and 98.5% viability and a transformation efficiency of 75.4% was achieved. This optimized protocol for protoplast isolation and transformation was successfully applied to eight representative cannabis varieties, which highlight the versatility and robustness of this technique. Using this protocol, the nuclear localization of a basic helix-loop-helix transcription factor (CsMYC2) was visualized, and the transcriptional activity of CsMYC2 was assessed. These results demonstrate the effectiveness of our cannabis protoplast isolation and transient transformation method that should serve as a powerful molecular research tool in a wide range of molecular studies.
Effect of seed coat mucilage, temperature and photoperiod on germination of four Arabian Desert species
(Canadian Science Publishing, 2021-12-22) Gairola, Sanjay; Mahmoud, Tamer; AlKetbi, Asma Mohammed; Shabana, Hatem Ahmed; Carón, María Mercedes; El-Keblawy, Ali
In this study, we assessed the effects of mucilage presence, thermoperiod, and photoperiod on seed germination percentage and germination velocity (mean germination time) of four Arabian desert species. We hypothesized that mucilage presence, thermoperiod, and photoperiod and their interaction would influence seed germination. Seeds with and without mucilage were germinated under different alternating temperature regimes of 15/25° C, 20/30 and 25/35° C, night/ day temperatures with a 12 h/0 h light/dark photoperiod. Results show that the incubation temperature affected the germination of all the studied species. Photoperiod significantly affected the germination of Boerhavia elegans, Salvia aegyptiaca, and Sporobolus ioclados, while the mucilage presence influenced the germination of only S. ioclados. The interaction between mucilage presence, temperature, and photoperiod significantly influenced the germination percentage of B. elegans and S. aegyptiaca. Neither removal of the mucilage nor light conditions affect the germination percentages of Sporobolus spicatus. However, the temperature affected the germination of S. spicatus. The germination of all the studied species was faster for demucilaged seeds. Ecologically, the mucilaginous seed coat is considered an important adaptation for dispersal as it anchors seeds on the ground, and holds water around the seed during the germination stage in the stressful arid deserts habitats.
Hypersensitive response-like cell death and its key related genes in the lmd lesion mimic mutant of birch
(Canadian Science Publishing, 2021-12-20) Li, Ranhong; Ning, Xiaomeng; Liu, Dan; Chen, Xin
Abstract: Lesion mimic mutants (LMMs) often display hypersensitive response-like (HR-like) cell death and enhanced resistance to pathogens. LMMs have been viewed as useful for the study of the mechanism of cell death and plant immunity. To date, few LMMs have been found in woody plants. We previously identified an LMM termed lmd, that showed spontaneous cell death in birch. In the current study, we investigated lmd, oe21 (transgenic control), and NT (non-transgenic control), focusing on cell death and gene expression profile of lmd. We found that cell death in the lmd occurred gradually during leaf development. The number of necrotic spots increased as the leaf developed, with no significant change in spot size. Subcellular observations showed degradation of both mitochondria and chloroplasts in lmd cells but not in NT and oe21 cells. Autophagosomes were visible in dying cells of lmd. We then performed RNA-seq of the four most-apical leaves of lmd and oe21 to explore the gene expression profile during cell death. Genes that were functional in signal perception, respiratory burst, signal transduction, and defense were enriched. TGA1, WRKY33, WRKY40, Chitinase, FLS2, RbohA/D and SBT were identified as key genes involved in cell death in lmd.
Origin of Symphyotrichum anticostense (Asteraceae: Astereae), an endemic, high polyploid species of the Gulf of St. Lawrence region, based on morphological and nrDNA evidence
(Canadian Science Publishing, 2021-10-27) Vaezi, Jamil; Brouillet, Luc
Symphyotrichum anticostense (Fernald) G.L.Nesom (Asteraceae: Astereae), a rare endemic of the Gulf of St. Lawrence region is a high allopolyploid (2n=10x=80). It has been hypothesized to be derived from the hybrid between tetraploid (2n=4x=32) individuals of S. boreale (Torr. A.Gray) Lve Lve and the hexaploid (2n=6x=48) S. novi-belgii (L.) G.L.Nesom. We investigated this hypothesis using morphological and molecular ITS-sequence data, and we tried to determine the potentially geographic origins of the taxon. Univariate morphological analyses show that 67.5% of the S. anticostense characters are parent-like, 43.5% from S. novi-belgii and 13% from S. boreale, the remainder not differing statistically from either parent; 23.5% are intermediate; and 9% transgressive. Multivariate analyses show that S. anticostense is intermediate between its putative parents. The molecular results support the morphological data, but due to the insufficient resolution among ribotypes on the tree, a more rapidly evolving marker will be needed to ascertain more reliably the origin of S. anticostense. Besides the hypothesis of genetic drift and allele fixation following long-distance dispersals, at least three independent geographic origins may be suggested for S. anticostense; Anticosti Island, Lake St. John, and Gasp Peninsula-New Brunswick-Maine.
Morphological and molecular identification of new records and new host plants of powdery mildews (Erysiphaceae) from Mexico
(Canadian Science Publishing, 2021-12-20) Gregorio-Cipriano, Rosario; González, Dolores; Félix-Gastélum, Rubén; Chacón, Santiago
Powdery mildew is one of the most severe diseases affecting Cucurbitaceae. We identify the members of Erysiphaceae infecting cucurbits in three producing regions in Mexico. We determined that Golovinomyces ambrosiae, Neoerysiphe sechii, and Podosphaera xanthii infected cultivated and wild cucurbits species or subspecies. Leaf samples showing symptoms and signs of powdery mildew were collected from the northwestern, central western, and eastern regions of Mexico between 2017 and 2020. Species associated with the disease were identified based on morphology and ITS rDNA sequences. All powdery mildew specimens presented only the anamorph. Podosphaera xanthii was the predominant species; it was found in 85.7 % of the samples and in 13 out of 14 species or subspecies of cucurbits. Neoerysiphe sechii was found in 15.23 % of the samples and in only four cucurbit species from the central western and eastern regions of Mexico. Golovinomyces ambrosiae was documented for the first time in a Cucurbitaceae species (Sicyos deppei) from Central West Mexico. Three new hosts were registered for Neoerysiphe sechii (Cucurbita ficifolia, Echinopepon milleflorus, and Sicyos laciniatus) and eight for Podosphaera xanthii (Cucurbita argyrosperma, C. argyrosperma subsp. sororia, C. ficifolia, C. okeechobeensis subsp. martinezii, C. radicans, Sechium edule, Sicyos laciniatus, and S. deppei).
Analysis of MYB genes in four plant species and the detection of those associated with drought resistance
(Canadian Science Publishing, 2021-10-20) Zhou, Yanli; Lu, Lin; Liu, Ningyawen; Cao, Hua; Li, Han; Gui, Daping; Wang, Jihua; Zhang, Chengjun
MYB transcription factor, which contains a conserved DNA-binding domain, has been found in almost all eukaryotes. MYB genes have variable functions in plants and are involved in many pathways. We systemically analyzed the MYB gene family in three Ericaceae species, Rhododendron williamsianum, Rhododendron delavayi, and Vaccinium corymbosum, and one outgroup, Actinidia chinensis, with 99, 156, 480, and 185 MYB genes found, respectively. The MYB genes were classified into five types based on the number of conserved MYB motifs, and the two repeat (2R) types were dominant in all four species. The percentage of 2R type MYB ranged from 48.5% to 87.9% in different species. We further classified the conserved MYB motifs into M1, M2, and M3 types based on motif definition. We found an abundance of 3xM2 type in the 3R group, but a species-specific type preference for 1R and 2R genes. On searching for Arabidopsis drought-resistant genes, we detected 34 potential candidates in four species. The expression profile of R. delavayi showed 11 candidate drought-resistant RdMYB genes, which provide a potential molecular design target for breeders. Our results describe the MYB gene family in these four species and could play an important role in future analyses.
An assessment of data accuracy and best practice recommendations for observations of lichens and other taxonomically difficult taxa on iNaturalist
(Canadian Science Publishing, 2021-11-29) McMullin, Richard Troy; Allen, Jessica L.
We assess the identification accuracy of research grade observations of lichens posted on the online platform iNaturalist. Our results show that these observations are frequently misidentified or lack the necessary chemical and/or microscopic information for accurate identification. Lichens are a taxonomically difficult group, but they are ubiquitous and eye-catching and are regularly the subject of observations posted on iNaturalist. Therefore, we provide best practice recommendations for posting lichen observations and commenting on observations. Data from iNaturalist are a valuable tool for understanding and managing biodiversity, particularly at this crucial time when large scale biodiversity decline is occurring globally. However, the data must be accurate for them to effectively support biodiversity conservation efforts. Our recommendations are also applicable to other taxonomically difficult taxa.
A rapid method for sex identification in Cannabis sativa using High Resolution Melt (HRM) analysis.
(Canadian Science Publishing, 2021-10-26) Gilchrist, Erin Jacqueline; Hegebarth, Daniela; Wang, Shumin; Quilichini, Teagen D.; Sawler, Jason; Toh, Shir Yi; Foley, Cody; Page, Jonathan E.
We report the identification of two SNPs in Cannabis sativa that are associated with female and male plant sex phenotypes, and are located on the top arm of the X chromosome. High Resolution Melt analysis was used to develop and validate a novel, rapid method for sex identification in medical/recreational cannabis as well as in hemp. This method can distinguish between dioecious male (XY) and dioecious female (XX) cannabis plants with 100% accuracy, and can also be used to differentiate between male and female Humulus lupulus (hop) plants.
Leaf structural traits of two Restinga plant species with different resistance pattern to iron toxicity
(Canadian Science Publishing, 2021-09-25) Santana, Brenda Vila Nova; Siqueira-Silva, Advanio Incio; Arajo, Talita Oliveira; Campos da Silva, Luzimar
Iron mining activities are a source of particulate iron, which contaminates soil and plants of Restinga biome (Brazil). To investigate the possible effects of iron toxicity to Ipomoea pes-caprae and Canavalia rosea leaves, plants were submitted to different exposure times (12, 36, 108 and 228 hours) and iron concentrations (0.5 or 150 mg L-1, Fe2+ as FeSO4.7H2O). After 108 hours C. rosea leaves were chlorotic while I. pes-caprae leaves presented venal chlorosis and bronzing after 228 hours, both from iron excess treatment. The anatomical alterations in I. pes-caprae were more intense and appeared earlier than in C. rosea, after 36 hours exposed to iron excess. The leaf epidermal cells of I. pes-caprae presented alterations in organization, size and shape and for both species the epicuticular wax was altered and wax rupture occurred close to the stomata. The positive staining for the presence of iron in leaf tissues matches with damaged areas in I. pes-caprae leaves, indicating direct iron toxicity. I. pes-caprae was the species with the most severe symptoms while C. rosea was the most resistant one. The results support that over time, the emission of particulate matter may negatively impact the ecological succession and biodiversity of Restinga.
Post-fire peatland vegetation recovery: A case study in open rich fens of the Canadian boreal forest
(Canadian Science Publishing, 2021-10-31) Gun Nanchen, Mlina; LeBlanc, Marie-Claire; Rochefort, Line
Fire plays a major role in structuring and the functioning of boreal ecosystems. As peatlands are important components of boreal forests, the impact of fire upon these wetter ecosystems is increasingly studied, but with the main focus on treed peatlands and Sphagnum-dominated bogs so far. Important fires occurring more frequently in the past decade in southern Northwest Territories (Canada) provide the opportunity to assess early post-fire vegetation regeneration in open rich fens (1, 2 and 5-years post-fire) and to better understand early recovery succession. We aimed to 1) evaluate whether and how open rich fens are affected by fire 2) describe short-term vegetation regeneration, for both bryophytes and vascular species. A shift was observed between pioneer bryophytes and brown mosses between the second and fifth-year post-fire. Vascular plants, especially slow-growing species and the ones reproducing mainly by seeds, recovered partially. The first bryophyte species recovering were pioneer species adapted to colonize burned environment such as Marchantia polymorpha or Ceratodon purpureus. For vascular plant species, the ones previously present and capable to regrowth rapidly from unburned plant structures (base of tussocks, rhizomes, roots) were represented by species like Betula glandulosa or Carex aquatilis. The wetter conditions and lower fuel availability of fen depressional biotopes were important factors controlling the resistance and regeneration of species associated with them.
Host ancestry and morphology differentially influence bacterial and fungal community structure of Rhododendron leaves, roots, and soil
(Canadian Science Publishing, 2021-09-03) Medeiros, Juliana S; Mann, Michael A; Burns, Jean H.; Kyker, Sarah; Burke, David
Rhododendron are popular ornamental plants which are well-known for forming mycorrhizal associations with ericoid fungi, but little is known about how host traits influence their microbiome more broadly. This study investigated leaf, root, rhizosphere soil, and bulk soil bacterial and fungal community structure for 12 Rhododendron species, representing four taxonomic clades with different leaf habits. Samples were collected when ephemeral hair roots colonized by ericoid mycorrhizae were absent, and microbial community structure was compared to leaf and root morphology for the same plants. Root morphology and the fungal communities of roots and rhizosphere soil were primarily structured by host ancestry. Leaf bacterial and fungal communities were even more distinct across clades than for roots or rhizosphere, and microbial communities of leaves and bulk soil were similarly structured by clade-wise differences in leaf morphology, suggesting a role for Rhododendron leaf litter in belowground microbial community structure. This work sheds new light on host traits influencing microbial community structure of ericaceous plants, showing a strong influence of ancestry, but also that different host traits drive bacterial and fungal communities across different plant compartments, suggesting future work on factors that drive similarity among close relatives in the non-ericoid microbes associating with Rhododendron.
Reference values for germination and emergence measurements
(Canadian Science Publishing, 2021-11-23) Ferreira, Wanessa Resende; Ranal, Marli A.; Santana, Denise Garcia
Why should we care about reference values for germination and emergence measurements? Because they can help in the conservation of species and thus the recovery or restoration of altered areas. Therefore, for the first time, we evaluated the germination and emergence processes of diaspores of five Cerrado species to propose reference values for the germination and emergence measurements to enable species comparison, and consequently, facilitate better conservation decisions. The five species have diaspores with high physiological quality and intraspecific variability in relation to the majority of the germination and emergence measurements, showing that they still retain their reproductive potential. The processes of seed germination and seedling emergence of Anadenanthera colubrina and Ceiba speciosa and seedling emergence of Astronium urundeuva were faster and more synchronised than those of Cedrela fissilis (emergence) and Lithraea molleoides (germination and emergence), indicating the presence of dormancy in the diaspores of the last two species. However, considering the reference values determined here, all the species could be considered very slow and very asynchronous. This means that all the species use large environmental windows to establish themselves, where the spreading of seed germination and seedling emergence over time is an important survival advantage.
Chromosome number, heterochromatin and genome size support recent polyploid origin of the Epidendrum nocturnum group and reveal a new species (Laeliinae, Orchidaceae)
(Canadian Science Publishing, 2021-08-27) Cordeiro, Joel M. P.; Chase, Mark W.; Hgsater, Eric; Mendona de Almeida, Erton; Costa, Lucas; Souza, Gustavo; Nollet, Felipe; Felix, Leonardo Pessoa
The Epidendrum nocturnum group comprises about 60 species. Nine species occur in Brazil, predominantly in the Atlantic and Amazon Forests. The group is taxonomically complex because its species are morphologically similar and not easily distinguished. The main objective of this work is to characterize their chromosome evolution and how this has affected species delimitation in Brazilian representatives of the E. nocturnum group. We used chromosome numbers, heterochromatin band patterns and genome size variation to better understand the chromosome variation, species delimitation and relationship among seven representatives of this group. A new species from Cerrado/Amazon rainforest ecotone is described based on cytological and morphological characters. The new species, Epidendrum pareciense, is a diploid (2n = 40), E. bahiense, E. carpophorum, E. micronocturnum, E. purpureocaulis and E. nocturnum are tetraploids (2n = 80), and E. tumuc-humaciense is hexaploid (2n = 120), the last a new ploidy for the group. Heterochromatin in these species is characterized by GC-rich regions (CMA
Leaf ontogenesis of Trembleya phlogiformis DC. (Microlicieae, Melastomataceae): functional aspects and indumentum characterization
(Canadian Science Publishing, 2021-10-21) Lima, Jamile Fernandes; Silva, Kleber Resende; Simo, Daniela Guimares; Coelho Kuster, Vincius; Oliveira, Denis
Leaf ontogenesis is determinant for the establishment and regulation of its structural and functional properties, in addition to being an excellent tool for assignment to different groups of angiosperms. Even though the importance of leaf morphology and anatomy for taxonomic use is well known, few studies have addressed the processes of leaf ontogeny in Melastomataceae. Herein, we sought to define the ontogenetic steps of leaf of Trembleya phlogiformis, highlighting the indumentum, to understand the main functional traits. Shoot apex, young and fully expanded leaves were processed by usual light microscopy procedures. At the first node, leaf primordia are densely covered with trichomes and emergences. The adaxial layer of ground meristem gives rise to the palisade parenchyma, the procambium originates from median layers of ground meristem and the spongy parenchyma develops from abaxial layers of ground meristem. The differentiation of isobilateral mesophyll on leaves of T. phlogiformis, a common feature in Microlicieae, comes from ground meristem stratification. However, T. phlogiformis stands out by showing in the leaf mature spongy parenchyma cells with irregular shapes. The leaf ontogeny reveals distinct mechanisms of cell differentiation and may be important for the establishment of functional adaptive traits. Key words: Leaf anatomy, development, histogenesis, glandular emergence, glandular trichome.
Reproductive phenological shifts and other phylogenetic trait changes in the Arbutoideae (Ericaceae) in the context of drought, seed predation, and fire.
(Canadian Science Publishing, 2021-11-04) Parker, V. Thomas; Stickrod, Morgan A.
Phenology is an ecologically critical attribute that commonly is coordinated with other plant traits. Phenological shifts may be the result of evolutionary adjustments to persistently new conditions, or transitory, varying with annual flux in abiotic conditions. In summer-dry, fire-prone Mediterranean-climates, for example, many plant lineages have historically migrated from forests to more arid shrublands resulting in adaptive trait changes. These shifts in habitat abiotic conditions and biotic interactions influence morphology of flowers and fruits and will interact with phenological timing. The Arbutoideae (Ericaceae) is one lineage that illustrates such modifications, with fruit characters evolving among genera from fleshy to dry fruit, thin to stony endocarps, and bird to rodent dispersal, among other changes. We scored herbarium collections and used ancestral trait analysis to determine phenological shifts among the five Arbutoid genera found in semi-arid climates. Our objective was to determine if phenology shifts with the phylogenetic transition to different reproductive characters. Our results indicate that phenological shifts began with some traits, like the development of a stony endocarp or dry fruits, but not with all significant trait changes. We conclude that early phenological shifts correlating with some reproductive traits were permissive for the transition to other later character changes.
Morphophysiological dormancy and germination ecology in diaspores of the subtropical palm Phoenix canariensis Chabaud
(Canadian Science Publishing, 2021-10-17) He, Lanlan; Jaganathan, Ganesh K.; Liu, Baolin
The timing of germination is a crucial event in a plant’s life cycle. Seed dormancy and germination mechanisms are important factors regulating seedling emergence. Since detailed experimental evidence for germination pattern of Phoenix canariensis colonizing sub-tropical climate is scarce, we investigated seed dormancy and germination ecology of P. canariensis. We found that the embryo is underdeveloped at the time of dispersal and doubles in size before the cotyledonary petiole (CP) protrudes through the operculum. The primary root and plumule emerge from the elongated CP outside the seed. In light/dark at 30/25C, the CP emerged from 8% of the diaspores within 30 days and from 76% within 14 weeks. Thus, 8% of the diaspores have MD and the others MPD. Removal of the pericarp and operculum resulted in 100% germination within 5 days in light/dark at 30/25C. Cold and warm stratification as well as treatment with GA3 significantly increased the germination speed, but the final germination percentage was not significantly increased. Seed germination was synchronized in early summer when seed dormancy was released by cold stratification in the soil over winter. A remote-tubular germination type and intricate root system provide an ecological advantage to the seedling establishment.
Lemon maturation causes anatomical and biochemical changes at the flavedo tissue level
(Canadian Science Publishing, 2021-09-08) Albornoz, Patricia L.; Interdonato, Roque; Hammann, Ariadna; Rosa, Mariana; Prado, Fernando E.; Rapisarda, Viviana A; Hilal, Mirna
Plants mobilize the photosynthates by three transport pathways: apoplastic, symplastic through plasmodesmata (PD), and transcellular. In flavedo of postharvest mature lemons, a high activity of cell wall-bound invertase (WI), an enzyme associated with transcellular transport of monosaccharides, has been detected. In order to elucidate whether this high enzymatic activity is related to restricted transport in the symplastic pathway with fruit maturation, the aim of the present work was to compare anatomical and biochemical parameters in peel tissues of immature and mature lemons. Anatomical structure focusing on cell walls, callose deposition, WI activity, and sucrose content were analyzed in peel tissues of immature and mature lemons. The parenchyma of flavedo tissue of immature lemons presented an elevated number of primary pit fields (PPF). These PPF, associated to PD or cell wall interruptions, had the appearance of a string of beads. However, in mature lemons, the number of PPF was scarce due to callose deposition. WI activity and apoplastic sucrose content increased significantly in flavedo of mature lemons in comparison to immature lemons. Present findings lay structural and functional bases relevant to understand differences between immature and mature lemons, which would help to design agricultural practices in pre- and post-harvest management.
Measurement of inbreeding depression in Rhododendron kaempferi: seed production, germination, juvenile survival, and growth
(Canadian Science Publishing, 2021-10-05) Takahashi, Keigo; Itino, Takao
To understand the reproductive ecology of a plant species with both selfing and outcrossing reproductive systems, it is important to know how selfed individuals contribute to the maintenance of a population. Further, examination of the magnitude of inbreeding depression after pollination is essential for accurate measurement of reproductive success. In this study, we investigated the characteristics of viable seeds and seedlings of Rhododendron kaempferi in a region where the bumblebee pollinator Bombus ardens are abundant. In a hand-pollination experiment, the fruit set from self-pollination was 32%, significantly lower than that from outcross-pollination (81%). The number of seeds per fruit from self-pollination was one sixth the number from outcross-pollination. However, the number of seeds per fruit was negatively correlated with the weight per seed. In addition, the germination rate was low when the seed weight was light. Although selfed seeds could germinate, 89% of the seedlings died within a year. The inbreeding depression coefficient 1 year after sowing was very high (0.89). These results indicate that R. kaempferi shows extremely strong selection for outcrossing but maintains a slight selfing potential in a natural population in central Japan.
Embryo position of Castanopsis sclerophylla (Fagaceae) seeds with recalcitrant storage behavior differs from Quercus genus, but response to desiccation shows no difference
(Canadian Science Publishing, 2021-09-15) Li, Jiajin; Jaganathan, Ganesh K.; Kang, Han; Liu, Baolin
In many -but not all- recalcitrant Quercus seeds, water loss during drying only occurs through the scar. Consequently, the embryo axis sitting on the opposite side of the scar is well protected from desiccation. However, whether such a mechanism is common throughout Fagaceae species is unexplored. Similarly, little is known about the desiccation response of other Fagaceae genera. Germination and desiccation tolerance of Castanopsis sclerophylla (Fagaceae) were studied by drying the seeds with silica gel. Fresh seeds had a moisture content (MC) of 36% and germinated to 92.5% when incubated at 15/20C. Drying seeds to 22.5 and 20.7% MC decreased germination to 27 and 5%, respectively; indicating that seeds are recalcitrant. X-ray computed tomography and photomicrographs showed that the embryo axis of C. sclerophylla is located just below the scar. Regardless of drying occurring either through only scar or the whole pericarp, embryo drying was deemed unavoidable. Nevertheless, germination percentage during drying showed exceptional similarities with the other Fagaceae species.
Allelopathic effects of native and exotic Prosopis congeners in Petri-dishes and potting soils: Assessment of the congeneric approach
(Canadian Science Publishing, 2021-08-23) tsombou, Franois Mitterand; El-Keblawy, Ali; Elsheikh, Elsiddig A.; AbuQamar, Synan F.; El-Tarabily, Khaled Abbas KA
The congeneric approach assesses the relative role of exotic invasive compared to native plants on associated species. However, most studies on seed germination were conducted in Petri-dishes that do not reflect natural soil conditions. Here, we compared the effects of different litter extracts of the exotics Prosopis juliflora and P. pallida and native P. cineraria on seed germination and seedling dry weight of two weedy (Amaranthus graecizans and Sisymbrium irio) and the native Senecio flavus in Petri-dishes and potted soil experiments. The results indicate that non-treated seeds (control) of the three species attained more than 95% germination in the Petri-dishes (in vitro). The increase in the litter concentrations of both invasive Prosopis species inhibited the native S. flavus germination and significantly reduced germination and seedling weight of the weedy A. graecizans and S. irio. Nevertheless, the native P cineraria extracts had significant depressive effects on seed germination and seedling growth of the native S. flavus but limited effects on the weedy A. graecizans and S. irio. The results support a greater impact of exotic than native congener on native plants. It is recommended not to rely mainly on germination in Petri-dishes for assessing allelopathic effects.

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